The Journal of Australian Ceramics Vol 49 No 1 April 2010

Focus: Wood -Firing
practice as a wood-firer or to help me answer those awkward questions that popped up at parties_ But
what I found was a concern about carbon em issions which did not just focus on the use of wood and
which overshadowed my concerns about forestry practices - how can I justify the release of over 60
tonnes of C02 each year from my kiln firings?
Essentially, although the source of carbon doesn't matter in relation to the amount of carbon dioxide
released, the source of the carbon is significant in regard to the impact on global warming. Over the
last two hundred years, the release of carbon that was removed from the atmospheric carbon cycle
and stored as coal and oil over millions of years has steadily increased the carbon dioxide levels in the
atmosphere. This has some beneficial effects, such as improving plant growth, but its major negative
impact is that, to date, it is has raised the average temperature of the atmosphere by 0.6°C, and is
heading inevitably towards a rise of two or three degrees. After the Copenhagen conference, we all
know that the reality of doing anything significant about it at a national and international scale is
politically difficult. In order to restrict temperature rise to the target of 2°C, each of the nine billion
people who will live on Earth by the year 2050 will have to restrict their release of carbon dioxide from
fossil fuels to two tonnes per person. In his writings Steve Harrison has covered many of the things that
he does, and that all of us should be doing, to lessen our 'carbon footprint'.2
We can do things as individuals, and I contend that wood-firing is one of the choices, considering
wood is one of a few genuinely renewable fuels. To quote from my 1989 paper:
" Compared to wood (and methane produced from a methane digester) al/ other fuels for
kilns release carbon which has been removed from the atmospheriC carbon cycle by the
process of burial and conversion into coal or oiU"
The growth and then decay and decomposition of timber is a natural cycle in which carbon is
removed from the atmosphere by the process of photosynthesis, and then released back into the
atmosphere as carbon dioxide and methane by the decay or combustion of the timber at the end of the
life cycle of the tree.
Wood or biomass is regarded as a carbon neutral renewable resource. In Europe and the US, waste
from industry and forestry is converted into wood pellets for use in automated boiler systems for central
heating, and there have been suggestions that timber resources could be used for the production of
base-load green electricity. Ray Cavill provides a comparison of different energy sources that can be used
for the generation of electricity and the amount of greenhouse gases produced for each kilowatt hour
of power produced 4
Energy Source
(Coal-fired) Electricity
LPG
Native Forest
Plantation Forest (off cuts)
kg CO2 per KWhr
1.00
0.34
0.03
-0.06
These figures indicate that forest products used to generate electriCity would produce significantly less
greenhouse gases than other sources of energy and that "the use of off-cuts from sawm ill ing practices
from plantation timber grown on ex-farmland results in a net carbon sequestration " 5 due to the
sequestration of carbon in the product manufactured using the timber.
In Australia, our forest resources regularly burn. The Black Saturday fires in 2009 would have released
unimaginable quantities of carbon back into the atmosphere as carbon dioxide, but, even without that
fire, over time that carbon would have been released into the atmosphere. And over time, those forests
will once again remove that carbon.
There is a fossil carbon component in the cutting and transportation of wood for the use in kilns, and
26 THE JOURNAL OF AUSTRALIAN CERAMICS APRil 2010